Unit 2: Of Skulls and Teeth

1. Unit 2: Of Skulls and Teeth

2. Introduction • An animal’s teeth and the skull the teeth are anchored in can tell you a great deal about the owner. • They tell how the vertebrate… • feeds • senses its environment • communicates with other organisms • defends itself against enemies

3. Exercise 1. Tooth Types & Diet Types • Tooth size, shape, and arrangement in the mouth are important determinants of the type of food an animal can obtain and consume. • Teeth can be used to tell what type of diet an animal has. • Four major groups of animals with respect to diet • carnivore (meat eater) • herbivore (plant eater) • insectivore (insect & worm eater) • omnivore (an animal that eats a variety of foods including meat and plants).

4. Tooth Types (List A) • Incisors are the flat, chisel-shaped teeth at the front of the mouth (behind the lips) that are used in biting, cutting, nibbling, and stripping. • Canines are behind the incisors, and are located on the cheek-side of the mouth. They are cone-shaped, and may even be dagger-like. They are used for seizing, piercing, and tearing. • Premolars are transitional teeth located between the canines and the molars at the rear. They have 1 or more cusps (points), and are generally used for grinding and crushing, but they may also be used in slicing food. • Molars have many major cusps (e.g., 3-5), and are located in the back of the mouth on the cheek side. Molars function in grinding and crushing.

5. Figure 1. Ventral view of skull showing location and structure of teeth.

6. Diet Types (List B) - Carnivores • Carnivoresshare special adaptations for life as predators. • Large slicing canines for piercing the skin of prey, and for cutting and chewing meat • Pointed incisors for tearing flesh • Even the cusps on a carnivore’s molars are high and pointed, because these teeth too are used in tearing and chewing flesh. • Long roots on all teeth so that they are well anchored for working on the tough food material • Carnivores also have front facing eyes, heavy skulls that support the large muscles needed to work the jaws, and jaws that are very strong but that move only up and down, not from side to side. Pictures of carnivore teeth on next slide

7. Carnivore Teeth Incisor Canine Molar Incisors showing long roots

8. Diet Types (List B) - Herbivores • Herbivoresfeed on plant material. They need to clip green leafy material off from grass roots (grazers) and tree branches (browsers). The cellulose in leaves is ground down into a mash that can be more easily digested. • Incisors have a flat cutting edge, for use in clipping off plant stems. Since these teeth wear down from this work, there is continuous tooth growth in many species. • Canines are often lacking entirely, as the food does not need to be captured, though squirrels may have pointed incisors that look like canines, which they use to break nuts open. • Molar teeth are tall and very broad. They have flat upper jaw surfaces sometimes with ridges on them to help grind plant material. Herbivore teeth on next slide

9. Herbivore Teeth Molar Incisor Deer Molar

10. Diet Types (List B) - Insectivores • Insectivoreshave a mouthful of sharp little peg-like teeth that are similar in size and shape. • These are used in seizing and crushing hard-shelled insects, and for gripping on to worms as they are pulled from their burrows.

11. Diet Types (List B) - Omnivores • Omnivoreshave the most variable teeth, used for eating both plant and animal material that make up their broad diet. • Incisors are more shovel-shaped than pointed • Long, sharp canines are used for puncturing and grabbing onto animal prey. • Wide molar and premolar teeth handle both the chewing of meat and the grinding of plant material. They have low bumpy crowns. incisors canine molar premolar

12. 1.Insectivore 2. Herbivore 4.Carnivore 3. Carnivore (toothless) 8. Omnivore 5. Herbivore 6. Herbivore 7. Omnivore 9. Carnivore 10.Omnivore 11. Herbivore

13. 3. Coyote (Canis latrans) - Carnivore • Dog relative that eats rabbits, mice, and other small rodents • The family Canidae is comprised of the thirty-three species of wild dogs (as well as domestic dogs, which represent numerous breeds of one species). • Canine teeth, often known as fangs, are used to hold prey, and in tearing flesh while eating. • Canids are cunning, skillful hunters with good hearing and acute senses of smell. • They utilize these skills to hunt and consume a variety of herbivorous animals.

14. 4. Mink (Mustela vison)- Carnivore • A mink is a weasel-like carnivore of the family Mustelidae • Size of a house cat; general color of dark chocolate brown • Mink prey chiefly on muskrats, but also eat mice, rabbits, chipmunks, fish, snakes, frogs, and birds. • They den (rear young) near water in burrows abandoned by other animals • Foxes, bobcats, and great horned owls are known predators of mink.

15. 5. Deer (Odocoileus virginianus) - Herbivore • Deer are considered browsers • feed on bushes, the lower branches of trees, and on bark • Deer belong to the mammalian order Artiodactyla, or even-toed herbivores. • In most species, only the male carries antlers - bony protrusions that are shed yearly, & are used in fights between males over females.

16. 6. Beaver (Castor canadensis) - Herbivore • Beavers are heavy-bodied aquatic rodents • best known for making dam homes • Rodentia is the largest order of living mammals • Beavers are the largest rodents in North America and Eurasia • They use their single pair of long front incisors to gnaw on trees and branches • Their incisors grow continuously throughout their lives

17. 7. Snapping Turtle (Chelydra serpentina) - Omnivore • Reptile with no teeth • Swallows food whole or tears it with its sharp beak • Major living orders of Class Reptilia: • 1. Chelonia (turtles & tortoises) • 2. Squamata (lizards & snakes) • 3. Crocodilia (crocodilians) • A fourth order (Sphenodontia) is represented by only two species of tuataras (similar to lizards) • Turtle palate divided into two sections separating food and air passageways so breathing can continue while food is being chewed

18. 8. Human (Homo sapiens) - Omnivore • Eats both plants and animals • ultimate omnivores • greatest variety of teeth of any animal, reflecting our broad diets • Human skull has an enormous cranial vault that protects a large brain for our complex thought processes • Large eye sockets • suggest the importance of vision to the survival of early man

19. 9. Bobcat (Felis rufus) – Carnivore • American cat species that eats small mammals • The cat family Felidae has 37 species that are found throughout the world • All cats share many tendencies, such as: • Large eyes and good vision. • Very sharp, retractable claws and long slender canine teeth.

20. 10. Skunk (Mephitis mephitis) – Omnivore • Among the most omnivorous of the flesh-eaters of the order Carnivora • Belongs to the family Mephitidae • Generally nocturnal • Live in a wide variety of habitats (open, wooded, scrub, agricultural, and even urban areas!) • Best known for their defensive smell, which is very offensive! • Use their keen sense of smell to locate food (such as rodents, frogs, fruit, berries, etc.)

21. 11.Porcupine (Erethizon dorsatum) – Herbivore • Eats bark, twigs, & leaves • Heavy-bodied rodent weighing 20 pounds • Powerful legs and long curved claws for climbing trees • Rump and tail are covered in over 30,000 barbed quills • protect the slow-moving porcupine from its main predators , the mountain lion, fisher, bobcat, and coyote.